Models | Notion

Existing Models

Name	Publication Year	What?	Relevancy
Computational (Neuro)phenomenology Model	2024	Uses a coupled classifier and generative deep neural network to simulate visual hallucinations.	• It can generate "synthetic VHs" characteristic of different aetiologies, including psychedelics.
• It considers key dimensions like realism, dependence on sensory input, and complexity.
• It uses Deep Convolutional Neural Networks (DCNNs) and Deep Generator Networks (DGNs), which could be adapted for our LSD-specific model.	https://doi.org/10.3389/fnhum.2023.1159821
Serotonin 2A (5-HT2A) Receptor Activation Model	2016	Directly relevant to LSD-induced hallucinations	• It focuses on 5-HT2A receptor activation, crucial for LSD's effects.
• It suggests that 5-HT2A receptor activation increases neuronal excitability and alters visual-evoked cortical responses.
• This mechanism could be incorporated into our computational model to simulate LSD's effects on cortical activity.	10.3390/ijms17111953
Visual Cortex AlterationsandThalamocortical Interactions	2017		• LSD increases functional connectivity between the primary visual cortex (V1) and other brain regions.
• It alters spontaneous activity in retinotopically organized areas of V1 and V3, even with eyes closed.
• These changes correlate with ratings of elementary or complex hallucinations.
• LSD-induced changes in thalamocortical connectivity are linked to visual and auditory alterations.
• This could be incorporated into our model to account for the role of thalamic gating in hallucinations.	10.1038/npp.2017.86
Rebeus Model

Ideas

5HT based Cortex model: 5HT-based cortex model will help explain the geometric visual hallucinations experienced during LSD use by highlighting the role of serotonin signaling in visual processing. LSD primarily targets the 5-HT2A serotonin receptors, which are prevalent in visual areas like the occipital lobe. This interaction disrupts normal visual processing and enhances pattern recognition, leading to vivid geometric shapes. Additionally, lower serotonin levels can reduce the brain's ability to filter sensory information, allowing more stimuli to enter consciousness. This overload prompts the brain to impose patterns on visual input, resulting in complex geometric hallucinations. Thus, the interplay between LSD and serotonin receptors significantly alters visual perception, producing these distinctive experiences.
Model including 5-HT only :
- 5-HT2A receptor activation as primary mechanism
- Model ↑ cortical excitability in visual processing areas
- Include modulation of alpha oscillations in the visual cortex
- Simulate changes in visual-evoked potentials, particularly the N170 component...
- Incorporate ↑ functional connectivity between V1 and other brain regions.
- Model alterations in spontaneous activity in retinotopically organized visual areas.
Model including 5-HT and DA with a primary focus on 5-HT2A receptors:
- Should model the interaction between 5-HT and DA systems, as they appear to have dissociable but complementary effects.
- Should include the fact that LSD ↓ DA neuron firing and DA receptor expression, as this could be important for understanding long-term effects.
- Should include the role of DA in cognitive aspects and perceived selfhood, while focusing on 5-HT for perceptual effects.